Thermodynamic Parameters for the Solvation of Monatomic Ions in Water

Fawcett, W. Ronald

doi:10.1021/jp991802n

Cited by 142 publications

(165 citation statements)

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“…65 There are several available sets of experimental hydration free energies available for comparison. [75][76][77][78][79][80][81] Hydration free energies and corrections calculated in this study are presented in Table III along with the experimental results of Tissandier et al, 77 Marcus et al, 76 and Schmid et al 75 Our corrected results ͑⌬G hyd real ͒ compare well with the data of Tissandier et al The larger anions ͑Br − and I − ͒ exhibit the greatest deviation from experiment, 7.5% and 3.0%, respectively. This is approximately the same accuracy obtained by Warren et al 82 for analogous anions in TIP4P-FQ.…”

Section: Single Ion Hydration Free Energiessupporting

confidence: 79%

Molecular dynamics simulations of nonpolarizable inorganic salt solution interfaces: NaCl, NaBr, and NaI in transferable intermolecular potential 4-point with charge dependent polarizability (TIP4P-QDP) water

Bauer

Patel

2010

The Journal of Chemical Physics

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We present molecular dynamics simulations of the liquid-vapor interface of 1M salt solutions of nonpolarizable NaCl, NaBr, and NaI in polarizable transferable intermolecular potential 4-point with charge dependent polarizability water ͓B. A. Bauer et al., J. Chem. Theory Comput. 5, 359 ͑2009͔͒; this water model accommodates increased solvent polarizability ͑relative to the condensed phase͒ in the interfacial and vapor regions. We employ fixed-charge ion models developed in conjunction with the TIP4P-QDP water model to reproduce ab initio ion-water binding energies and ion-water distances for isolated ion-water pairs. The transferability of these ion models to the condensed phase was validated with hydration free energies computed using thermodynamic integration ͑TI͒ and appropriate energy corrections. Density profiles of Cl − , Br − , and I − exhibit charge layering in the interfacial region; anions and cation interfacial probabilities show marked localization, with the anions penetrating further toward the vapor than the cations. Importantly, in none of the cases studied do anions favor the outermost regions of the interface; there is always an aqueous region between the anions and vapor phase. Observed interfacial charge layering is independent of the strength of anion-cation interactions as manifest in anion-cation contact ion pair peaks and solvent separated ion pair peaks; by artificially modulating the strength of anion-cation interactions ͑independent of their interactions with solvent͒, we find little dependence on charge layering particularly for the larger iodide anion. The present results reiterate the widely held view of the importance of solvent and ion polarizability in mediating specific anion surface segregation effects. Moreover, due to the higher parametrized polarizability of the TIP4P-QDP condensed phase ͕1.31 Å 3 for TIP4P-QDP versus 1.1 Å 3 ͑TIP4P-FQ͒ and 0.87 Å 3 ͑POL3͒ ͓Ponder and Case, Adv. Protein Chem. 66, 27 ͑2003͔͖͒ based on ab initio calculations of the condensed-phase polarizability reduction in liquid water, the present simulations highlight the role of water polarizability in inducing water molecular dipole moments parallel to the interface normal ͑and within the interfacial region͒ so as to favorably oppose the macrodipole generated by the separation of anion and cation charge. Since the TIP4P-QDP water polarizability approaches that of the experimental vapor phase value for water, the present results suggest a fundamental role of solvent polarizability in accommodating the large spatial dipole generated by the separation of ion charges. The present results draw further attention to the question of what exact value of condensed phase water polarizability to incorporate in classical polarizable water force fields.

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Section: Single Ion Hydration Free Energiessupporting

confidence: 79%

Molecular dynamics simulations of nonpolarizable inorganic salt solution interfaces: NaCl, NaBr, and NaI in transferable intermolecular potential 4-point with charge dependent polarizability (TIP4P-QDP) water

Bauer

Patel

2010

The Journal of Chemical Physics

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“…Helgeson and Kirkham [76] have shown that there is a linear correlation between the enthalpy of solvation of ions and the inverse of the effective ionic radius, while Marcus [77] has also demonstrated a correlation between the Gibbs free energy of solvation and the ionic radius. In Figure 2, we apply these observations to assess our choice of Born cavity diameters for the ions and find that they correlate linearly with the experimental Gibbs free energies of solvation [77][78][79]. This lends confidence to the values of σ with G solv, i can be used to estimate the cavity diameter of ions as an alternative to the approach of Rashin and Honig.…”

Section: Saft-vr Mie Electrolyte Modelsmentioning

confidence: 65%

Development of intermolecular potential models for electrolyte solutions using an electrolyte SAFT-VR Mie equation of state

et al. 2016

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We present a theoretical framework and parameterisation of intermolecular potentials for aqueous electrolyte solutions using the statistical associating fluid theory based on the Mie interaction potential (SAFT-VR Mie), coupled with the primitive, non-restricted mean-spherical approximation (MSA) for electrolytes. In common with other SAFT approaches, water is modelled as a spherical molecule with four off-centre association sites to represent the hydrogen-bonding interactions; the repulsive and dispersive interactions between the molecular cores are represented with a potential of the Mie (generalised Lennard-Jones) form. The ionic species are modelled as fully dissociated, and each ion is treated as spherical: Coulombic ion-ion interactions are included at the centre of a Mie core; the ion-water interactions are also modelled with a Mie potential without an explicit treatment of iondipole interaction. A Born contribution to the Helmholtz free energy of the system is included to account for the process of charging the ions in the aqueous dielectric medium. The parameterisation of the ion potential models is simplified by representing the ion-ion dispersive interaction energies with a modified version of the London theory for the unlike attractions. By combining the Shannon estimates of the size of the ionic species with the Born cavity size reported by Rashin and Honig, the parameterisation of the model is reduced to the determination of a single ion-solvent attractive interaction parameter. The resulting SAFT-VRE Mie parameter sets allow one to accurately reproduce the densities, vapour pressures, and osmotic coefficients for a broad variety of aqueous electrolyte solutions; the activity coefficients of the ions, which are not used in the parameterisation of the models, are also found to be in good agreement with the experimental data. The models are shown to be reliable beyond the molality range considered during parameter estimation. The inclusion of the Born free-energy contribution, together with appropriate estimates for the size of the ionic cavity, allows for accurate predictions of the Gibbs free energy of solvation of the ionic species considered. The solubility limits are also predicted for a number of salts; in cases where reliable reference data are available the predictions are in good agreement with experiment.

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“…28 The higher solubility observed for the acid form compared to the sodium salt is consistent with the solvation energy of a sodium ion being 162.7 kcal/mole less than that of a hydronium ion. 29 We observed a five-fold increase in current density with the free sulfonic acid form over the sodium salt form ( Figure 3); this increase in performance can only be attributed to the increase in concentration of the reactants and improved ionic conductivity of the membrane. The higher solubility of the acid form avoided the abrupt drop in cell voltage resulting from concentration polarization caused by inadequate mass transport, especially at high current densities and low states-of-charge.…”

Section: Resultsmentioning

confidence: 83%

High-Performance Aqueous Organic Flow Battery with Quinone-Based Redox Couples at Both Electrodes

Yang

Hoober-Burkhardt

Krishnamoorthy

et al. 2016

J. Electrochem. Soc.

196

265

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We have demonstrated the repeated cycling of a redox flow cell based on water-soluble organic redox couples (ORBAT) at high voltage efficiency, coulombic efficiency and power density. These cells were successfully operated with 4,5-dihydroxybenzene-1,3-disulfonic acid (BQDS) at the positive electrode and anthraquinone-2,6-disulfonic acid (AQDS) at the negative electrode. Reduction of the voltage losses arising from mass transport limitations, and understanding of the chemical transformations of BQDS during charging have led to these improvements in performance. The specific advances reported here include the use of organic redox couples in the free-acid form, improvements to the flow field configuration, and novel high-surface-area graphite-felt electrode structures. We have identified various steps in the chemical and electrochemical transformations of BQDS during the first few cycles. We have also confirmed that the crossover of the reactants through the membrane was not significant. The performance improvements and new understanding presented here will hasten the development of ORBAT as an inexpensive and sustainable solution for large-scale electrical energy storage. With the increasing penetration of solar photovoltaic and windbased electricity generation, the variable and intermittent output of these energy generation systems is a grave concern for stable operation of the electricity grid. To buffer the inevitable surges in electricity supply and demand, large-scale energy storage systems are needed. Such energy storage systems must be capable of storing thousands of giga-watt hours of electricity per day. Rechargeable batteries are particularly attractive for electrical energy storage because of their high energy efficiency and scalability.1-3 However, for such a largescale application, these batteries must be inexpensive, robust, safe, and sustainable. None of today's commercially-available batteries can meet all the performance and cost targets at this scale of deployment of energy storage. This situation has led to a global search for a transformational solution.In 2013, we described an organic redox flow battery -also known as ORBAT -that uses water-soluble organic redox couples as a safe, scalable, and efficient energy storage system with the potential to meet the United States Department of Energy (DoE) cost target of $100/kWh for large-scale energy storage. 4 In such a battery, aqueous solutions of two different water-soluble organic redox couples -quinones and anthraquinones or their derivatives -were circulated past carbon electrodes in an electrochemical cell. In our current system, the positive electrode is supplied with a solution of 4,5-dihydroxybenzene-1,3-disulfonic acid (BQDS) and the negative electrode uses a solution of anthraquinone-2,6-disulfonic acid (AQDS). The positive and negative electrode compartments are separated by a proton-conducting polymer electrolyte membrane (Figure 1). During charge and discharge, the redox couples undergo rapid proton-coupled electron transfer to store ...

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Thermodynamic Parameters for the Solvation of Monatomic Ions in Water

Cited by 142 publications

References 23 publications

Molecular dynamics simulations of nonpolarizable inorganic salt solution interfaces: NaCl, NaBr, and NaI in transferable intermolecular potential 4-point with charge dependent polarizability (TIP4P-QDP) water

Molecular dynamics simulations of nonpolarizable inorganic salt solution interfaces: NaCl, NaBr, and NaI in transferable intermolecular potential 4-point with charge dependent polarizability (TIP4P-QDP) water

Development of intermolecular potential models for electrolyte solutions using an electrolyte SAFT-VR Mie equation of state

High-Performance Aqueous Organic Flow Battery with Quinone-Based Redox Couples at Both Electrodes

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